ABSTRACT
The purpose of this chapter is to trace the propagation of errors for one class of GIS operations, which have been identified in the first chapter by the name of local operations. This term refers to operations, for which the value of the output map at some location only depends on the value of the input maps at that same location, or possibly on their values within not too large a window surrounding that location. Local operations thus include point operations and neighbourhood operations (figure 4.1). Examples of local operations are Multiply, Maximise, Smooth, Sqrt and Slope (Burrough, 1986; Tomlin, 1990; Burrough and McDonnell, 1998), or a combination of these, such as a multiple regression model (Heuvelink et al., 1989; Vereecken et al., 1989), a fuzzy classification model (Burrough, 1989a; Burrough et al., 1992) or a crop growth model (Van Diepen et al., 1989; Van Lanen et al., 1992).
